An internal combustion engine is provided with a main structural member or a main body such as a cylinder block and a cylinder head having a high stiffness, and the main body is typically provided with a bracket fastening part consisting of a rib extending in a circular or polygonal configuration and having a planar top surface. A plurality of threaded holes or stud bolts are provided along the rib. Each threaded hole or the stud bolt is surrounded by an annular projection (called as “boss”) having a top surface flush with the top surface of the rib. Such a bracket fastening part provides a flat surface for securing auxiliary equipment or any other component part to the main body of the engine. In particular, an engine bracket for supporting the engine to the vehicle body is normally attached to such a bracket fastening part of the engine. See JP5471368B2 and JP2002-266693A, for instance.
In the automotive industry, a same engine may be mounted in different vehicle models, and in same models of different grades. In such a case, various associated items of auxiliary equipment or brackets may be required to be attached to the same engine in different ways. For this reason, the engine may be provided with a plurality of bracket fastening parts to accommodate for the different ways in which the auxiliary equipment or brackets may be attached to the engine. Therefore, it is often necessary to provide bracket fastening parts which may be partly redundant in some of the applications of the engine. This obvious adds to the weight of the vehicle. In particular, the bosses provided along the rib of each bracket fastening part contribute to the increase in weight.